Effects of Different Extraction Methods on Structure and Functional Characteristics of Almond Protein

The objective of this study was to increase the utilization rate of almond protein (AP). In this study, the alkaline extraction by isoelectric precipitation (AI), thermal alkaline (TA) and salt extraction (SE) were used to extract AP, namely AIAP, TAAP and SEAP were to explore the effects of extraction methods on protein structure and functional properties. The results showed that the structure and function of AP were affected by different extraction methods. SEAP exhibited the highest protein extraction rate (55.94%) and purity (88.21%), while AIAP had the lowest protein purity (75.06%), and the extraction rate of TAAP was the lowest (50.71%). The surface of AIAP was rough and the structure was loose, while the structure of TAAP and SEAP was dense, and the β-sheet content of AIAP (44.97%) and surface hydrophobicity of AIAP were higher than that of TAAP and SEAP. Compared with TAAP and SEAP, AIAP showed higher water holding and oil holding capacity. The solubility of SEAP and TAAP was significantly higher than that of AIAP, and the protein exhibited superior emulsification and foaming properties. This study provides a theoretical reference for the application of almond protein in food industry.